Binary MnO₂/Co₃O₄ @ Well-aligned Electrospun Carbon Nanofibers for Sensitive, Nonenzymatic Glucose Sensing

A binary metal oxide composite, manganese oxide/cobalt oxide (MnO2 /Co3O4), on a well-aligned electrospun carbon nanofibers (MnO2/Co3O4@ECNFs) mat was synthesized via a simple one-step template-free electrodeposition process at a constant low-current (60 μA) for hours. The MnO2/Co3O4@ECNFs nanocomposite mat show excellent electrocatalytic activity towards sensitive and selective non-enzymatic glucose sensing. The MnO2/Co3O4@ECNFs nanocomposite were tested and characterized thoroughly by high resolution imaging and spectroscopic techniques. The results reveal that the binary metal oxides are uniformly deposited on the well-aligned ECNFs mat with high porosity, effective interconnectivity and large number of extended conducting channels. The electrochemical impedance spectroscopy (EIS) of the nanocomposite mat electrode show very good conductivity in 0.1 M KCl containing 5 mM [Fe(CN)6]3-/4-. The electrocatalytic activity of as-prepared MnO2/Co3O4@ECNFs for oxidation of glucose were performed by cyclic voltammetry (CV) and chronoamperometry (CA); and the experimental results demonstrate a superior sensing performance for glucose detection, including a rapid response (5 seconds), a wide dynamic range (up to 10.9 mM), excellent sensitivity of 973.91 μA mM-1 cm-2 and a detection limit of 0.02 μM (S/N=3) with satisfactory selectivity, reproducibility and stability. The plausible reactions involved for the electrocatalytic oxidation of glucose by the binary metal oxides are as follows.1 2Co02 + C6H1206 (glucose) -> 2Co00H + C6H1006 (gluconolactone) (1) 2Mn0 2 + C6H1206 (glucose) -> 2Mn00H + C6H1006 (gluconolactone) (2) Finally, the nanocomposite electrode was tested in glucose spiked human serum samples. The recovery rates of a series of standard glucose solutions are nearly 100%, suggesting the excellent performance and potential towards development of a nonenzymatic glucose biosensor for practical applications. Reference 1. Han, L.; Yang, D.-P.; Liu, A., Leaf-Templated Synthesis of 3d Hierarchical Porous Cobalt Oxide Nanostructure as Direct Electrochemical Biosensing Interface with Enhanced Electrocatalysis. Biosensors and Bioelectronics 2015, 63, 145-152.